JP3893069B2 - Automatic penetration testing machine and penetration testing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic penetration tester and a penetration test method for performing a penetration test while detecting vibrations propagated through the penetration rod when penetrating the penetration rod into the ground.
[0002]
[Prior art]
Conventionally, various penetration tests such as a standard penetration test, a Dutch double pipe cone penetration test, a Swedish sounding test, and a boring test have been performed in order to know the proof strength of a building planned construction site and the like. Each of these penetration tests is carried out by using a dedicated ground investigation machine. Among such ground investigation machines, a particularly popular penetration test machine is disclosed in Japanese Patent Laid-Open No. 8-292141. . This penetration testing machine generally has the following configuration.
[0003]
As shown in FIGS. 5 and 6, the conventional penetration testing machine 1 ′ has a lifting platform 4 that can load a weight 2 of a predetermined weight and can be lifted and lowered along a column 3. A chuck 5 is arranged. The chuck 5 is rotated by being driven by a chuck driving motor 6 which is an example of a rotation driving source, and the penetration rod 7 is held by the chuck 5 so as to rotate integrally. . The penetrating rod 7 includes a rod-shaped rod portion 71 that can be added and a drill-shaped screw point 72 attached to the tip of the rod portion 71.
[0004]
Further, a chain member 8 is provided on the column 3 so as to extend linearly, and a sprocket 9 that is rotatably attached to the lifting platform 4 is engaged with the chain member 8. By detecting the rotation of the sprocket 9 with the sensor 9a, the descending amount of the lifting platform 4, that is, the penetrating amount (penetration depth) of the penetrating rod 7 can be determined from the signal. A method for indexing the penetration amount of the penetration rod 7 is also known from Japanese Patent Application Laid-Open No. 9-111745.
[0005]
The sprocket 9 is connected to a lifting motor 11 through a transmission shaft 9b, a one-way clutch 10, and bevel gears G1 and G2, so that the lifting motor 11 is driven to rotate. It is configured. The driving of the lifting motor 11 is transmitted to the sprocket 9 only when the sprocket 9 is rotated in the direction in which the lifting platform 4 is lifted by the action of the one-way clutch 10. With this structure, when the penetrating rod 7 is penetrating into the ground, the elevating motor 11 is driven in a direction in which no rotation is transmitted to the sprocket 9, and the one-way clutch 10 is idled with respect to the sprocket 9. It is possible to prevent the lowering operation of the lifting platform 4 from being restricted by the reduction ratio. The transmission shaft 9b that rotates integrally with the sprocket 9 is connected to a powder brake 12 as an example of a brake means. The powder brake 12 can apply a braking force to the sprocket 9 stepwise. Yes. When the penetrating rod 7 is penetrating into the ground, a load based on the weight of the lifting platform 4 is applied to the penetrating rod 7 by the idling operation of the one-way clutch 10, but at this time, the powder brake 12 is actuated. By applying a predetermined braking force to the sprocket 9 to brake the rotation of the sprocket 9, the load due to the weight of the lifting platform 4 can be quickly and accurately changed finely.
[0006]
The penetration testing machine 1 automatically performs a sounding test according to the Swedish sounding test method of Japanese Industrial Standard A1221. In the test, a load (increase / decrease every 250 N, maximum 1 KN) based on the weight of the lifting platform 4 and the braking force applied by the powder brake 12 is applied to the penetrating rod 7, and the penetrating rod 7 rotates as necessary. By this, the penetration rod 7 penetrates into the ground.
[0007]
In the process of penetrating rod 7 penetrating into the ground, the penetrating speed of penetrating rod 7 changes according to the soil quality. Therefore, such as rotation application / stop, load change, etc. Intrusion conditions are changed. Each time the penetration condition is changed, the penetration amount of the penetration rod 7 during that period, the half rotation number of the penetration rod 7 (the rotation number obtained by counting one rotation of the penetration rod 7 as 2), and the load value are the control unit as test data. (Not shown). The control unit obtains the number of half revolutions per meter (hereinafter referred to as Nsw value) from this test data. Based on this Nsw value, it is possible to determine the ground strength at each penetration depth (hardness / tightness of the land, tightness, etc.) and know the ground strength of the land. The detailed structure, operation, and effects of the penetration testing machine 1 'are the same as those of the above-mentioned Japanese Patent Application Laid-Open No. 8-292141.
[0008]
[Problems to be solved by the invention]
In the test by the conventional automatic penetration tester, during the test, an operator listens and records the friction sound between the screw point transmitted through the penetration rod and the soil with the ear. In order to increase the reliability of the ground strength by recording the frictional sound that changes depending on the soil, estimate the soil quality at each penetration depth, and collate it with the ground strength determined based on the Nsw value. Actually, however, there was a difference in the sound that was obtained due to ambient noise at the test site, differences in sensitivity among workers, and the like. Therefore, recently, as shown in Japanese Patent Application No. 2000-35797, a microphone is provided in the penetration testing machine, and a sound is acquired by this microphone, and a sensor attached to the penetration rod as shown in Japanese Patent Application No. 2001-279844. A device that detects sound and wirelessly transmits the detection signal has been proposed, and a more accurate sound detection method and structure have been studied.
[0009]
However, the various sound detection means described above have the following problems. First, in the case of a structure in which sound is detected by a microphone, the sound propagated through the penetrating rod is once propagated in the air, so that the sound is attenuated and the original sound cannot be obtained. In addition, since noises in various surrounding bands are captured, it becomes impossible to identify the sound propagated through the essential penetration rod. Furthermore, the frequency band of sounds that can be collected is limited by the frequency characteristics of the microphone. On the other hand, in the case of a structure that wirelessly transmits the detection signal of the sensor directly attached to the penetrating rod, a transmitter, a receiver, and the like are required. Problems such as complicated control of the apparatus, such as control for transmission and reception, have occurred.
[0010]
[Means for Solving the Problems]
The present invention has been created in view of the above problems, a lifting platform that can be moved up and down along the support column, a chuck that is rotatably provided on the lifting platform, a rotation drive source that rotates the chuck, In an automatic penetration tester comprising a penetration rod that is detachably attached to the chuck and is held so as to be integrally rotatable, the automatic penetration testing machine is urged so as to always abut against the penetration rod or a rotation portion that can rotate integrally with the penetration rod. A shaft-shaped contact member provided, and a vibration detection unit that is attached to the contact member and detects vibration transmitted from the penetrating rod or the rotating part to the contact member. . The vibration detection sensor preferably detects a vibration caused by a frictional sound transmitted from the screw point to the contact member through the penetrating rod or a rotating portion that can rotate integrally with the penetrating rod . It is also desirable to have a means for allowing the rotation of the screw point due to the resistance of the soil when the penetration rod is scuttled.
[0011]
In the present invention, the penetrating rod is held by a chuck that is rotatably provided by the drive of the rotational driving source, and a load that is changed as necessary is applied to the penetrating rod, and rotation is performed as necessary. A shaft-shaped contact member that is arranged so as to continually abut on a penetration portion or a rotating portion that can rotate integrally with the penetration rod, by allowing vibrations propagated through the penetration rod to penetrate into the ground. And detecting the soil quality based on the detected vibration.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 3, reference numeral 1 denotes an automatic penetration testing machine, which has the same basic structure as the penetration testing machine disclosed in Japanese Patent Laid-Open No. 8-292141 introduced in the above-mentioned prior art section. is there. Therefore, here, the part related to the structure added in order to detect the sound propagated through the penetrating rod 7 will be described in detail.
[0013]
In the automatic penetration testing machine 1, the chuck 5 that holds the rod portion 71 is arranged in a vertically split two-piece bearing case 51 fixed to the lifting platform 4, and is rotatably disposed in the bearing case 51 via a bearing. A rotating sleeve 52; a rod holding sleeve 53 integrally connected to the upper portion of the rotating sleeve 52; a stopper member 54 slidably provided along the rod holding sleeve 53; And a locking member 56 that restricts the upper position of the stopper member 54.
[0014]
The rotating sleeve 52 and the rod holding sleeve 53 have an insertion hole 57 through which the rod portion 71 of the penetrating rod 7 can be inserted, and the rod holding sleeve 53 is equally arranged on the outer peripheral surface of the rod portion 71. The storage holes 53a for storing the steel balls 58 that are respectively locked in the three locking grooves 73 (one is not shown) are provided at positions that divide the cross section into three equal parts. These storage holes 53 a are always closed by the stopper member 54, so that the steel ball 58 is locked in the locking groove 73 of the rod portion 71 so that the penetration rod 7 can be held in the chuck 5. It is configured. The upper inner peripheral surface 54 a of the stopper member 54 is configured to have a large diameter so as to allow the operation of the steel ball 58, and the steel ball is pushed down by pushing the stopper member 54 against the bias of the spring 55. The rod portion 71 can be removed by making the 58 movable.
[0015]
A sprocket 59 is attached to the lower portion of the rotary sleeve 52 so as to rotate integrally. On the other hand, a sprocket 14 is connected to the output shaft 6 a of the chuck driving motor 6 disposed on the elevator 4 via a one-way clutch 13. An endless chain 15 is wound around these sprockets 14 and 59 so that the drive of the chuck driving motor 6 can be transmitted to the chuck 5.
[0016]
The one-way clutch 13 is configured to transmit this drive to the sprocket 14 when the chuck driving motor 6 is driven to rotate the screw point 72 in the screwing direction. Therefore, when the rotation in the direction in which the screw point 72 is screwed is transmitted from the chuck 5 side, the one-way clutch 13 rotates idly with respect to the output shaft 6a. That is, in this case, the chuck 5 and the penetrating rod 7 can freely rotate without receiving a rotational resistance due to the mechanical structure of the chuck driving motor 6. For this reason, when the penetration rod 7 penetrates into the ground only with a load, so-called self-sinking, the screw point 72 can be allowed to rotate due to the resistance of the soil.
[0017]
Further, the circumferential surface of the lower portion of the rod holding sleeve 53 is smoothed over the entire circumference, and is configured as a detection surface 53b with which the contact member 18 of the acoustic detection mechanism 16 to be described later always abuts. The detection surface 53b is covered with an upper portion of the bearing case 51 and a flange portion 53c of the rod holding sleeve 53, and is sealed with a rubber ring member 60 such as an oil seal or an O-ring, and a lubricant such as grease is enclosed. Has been. With this lubricant, the detection surface 53 b is rust-prevented and the frictional noise between the contact member 18 and the rod holding sleeve 53 is reduced.
[0018]
In addition, the acoustic detection mechanism 16 is attached to the bearing case 51. The sound detection mechanism 16 is integrally attached to the bracket member 17 fixed to the bearing case 51, a shaft-like contact member 18 slidably provided on the bracket member 17, and the contact member 18. And a vibration detection sensor 19 which is an example of the vibration detection means. The contact member 18 of the acoustic detection mechanism 16 is constantly urged toward the bearing case 51 by a spring 20, and a tip portion of the contact member 18 passes through the bearing case 51 and is always on the detection surface 53 b of the rod holding sleeve 53. It is comprised so that it may contact | abut. The contact member 18 is guided to the bearing case 51 and the bracket member 17 via resin bushes 21 and 22, respectively, and the bracket member 17 and the bearing case are formed by the resin bushes 21 and 22, respectively. For example, a noise element such as vibration caused by driving of the chuck driving motor 6 is absorbed, and is not transmitted to the contact member 18. Further, the front end surface of the contact member 18 is processed into a spherical shape, and the contact area with the detection surface 53b is reduced to suppress the generation of frictional sound here.
[0019]
During the penetration test in which the penetration rod 7 penetrates into the ground while obtaining the test data, the rod portion 71 has friction noise generated by contact between the screw point 72 at the tip and the soil (vibration; hereinafter referred to as friction noise vibration). Is propagated. This friction sound vibration differs depending on the soil quality with which the screw point 72 is in contact. The frictional sound vibration transmitted through the rod portion 71 is transmitted to the contact member 18 in contact with the detection surface 53 b of the rod holding sleeve 53 via the steel ball 58 and the rod holding sleeve 53. The vibration of the contact member 18 due to the frictional sound vibration is detected by the vibration detection sensor 19 and output to the control unit 23. At this time, when the elevating motor 11 is driven, the rod holding sleeve 53 and the penetrating rod 7 rotate integrally. At this time as well, the contact member 18 is always on the detection surface 53 b of the rod holding sleeve 53. Continue to abut. Therefore, the frictional sound vibration propagated through the rod portion 71 is reliably transmitted from the rod holding sleeve 53 to the contact member 18 and detected by the vibration detection sensor 19. Moreover, since the detection surface 53b is finished smoothly and the lubricity is enhanced by the lubricant, the frictional noise between the rotating rod holding sleeve 53 and the contact member 18 is sufficiently small to be negligible. Therefore, the frictional sound vibration detected by the vibration detection sensor 19 is extremely accurate.
[0020]
The detection signal of the frictional sound vibration by the vibration detection sensor 19 is sent to the control unit 23, converted into a digital signal by the A / D conversion unit 23a, amplified to a predetermined level through the amplification unit 23b, and then subjected to arithmetic processing. Sent to the unit 23c. In the arithmetic processing part 23c, the soil quality of the said area is determined by analyzing the detection signal of a predetermined area. The soil information determined in this way is recorded in the storage unit 23d in association with the penetration depth of the penetration rod 7 calculated from the rotation of the sprocket 9. At this time, in order to enable later recalculation, the original signal sent from the vibration detection sensor 19 is also sequentially recorded in the storage unit 23d corresponding to the penetration depth.
[0021]
Further, in the control unit 23, each time the load applied to the penetrating rod 7 is changed and rotation is applied / stopped, the load value up to that point and the half of the penetrating rod 7 after the previous test data acquisition are performed as in the prior art. The rotational speed is acquired as test data, and the Nsw value is obtained from this, and these are recorded in the storage unit 23d corresponding to the penetration depth of the penetration rod 7 at that time.
[0022]
After the penetration test is completed, the operator connects a personal computer (not shown) to the input / output interface 23e of the control unit 23, so that the soil information, test data, Nsw corresponding to the penetration depth recorded in the control unit 23 is obtained. Values can be imported into a personal computer. And based on these, the formation at the point where the test was performed can be finally determined. In addition, since the detection signal by the vibration detection sensor 19 is recorded in the control unit 23 as it is in correspondence with the penetration depth of the penetration rod 7, it is possible to reconfirm the friction sound at each depth by taking this into the personal computer. It becomes possible. Thereby, the soil quality determined by the control unit 23 can be checked, and the reliability of the determined soil quality can be improved.
[0023]
In the above description, the structure in which the contact member 18 of the sound detection mechanism 16 is always brought into contact with the rod holding sleeve 53 of the chuck 5 has been described. However, the contact member 18 of the rod portion 71 protruding above the chuck 5 is described. The sound detection mechanism 16 may be disposed so as to abut on the circumferential surface. Further, as shown in FIG. 4, an axial contact member 18 'is disposed on the coaxial line of the rod portion 71, and this contact member 18' is always in contact with the upper end surface of the rod portion 71 by the bias of the spring 20 '. An acoustic detection mechanism 16 'configured as described above may be provided. In these cases, each surface of the rod portion 71 with which the contact member abuts may be finished smoothly. As described above, according to the structure based on the technical idea of the present invention, the rotation that rotates integrally with the penetration rod 7 such as the rod holding sleeve 53 in the penetration rod 7 and the chuck 5 without using the conventional wireless transmission / reception means. Since it is possible to detect the frictional sound vibration from the site and no transmitter / receiver is required, the circuit structure and the like are extremely simple.
[0024]
The contact member 18 is brought into contact with the rotating portion of the chuck 5 that rotates integrally with the penetrating rod 7. In the chuck 5 that is rotationally driven, the chuck 5 is fixedly disposed on the portion that rotates integrally with the penetrating rod 7 and the lifting platform. It has been experimentally confirmed that there is a large difference in the level of the frictional sound vibration with the portion that is present. In other words, the frictional sound vibration obtained from the part rotating integrally with the penetrating rod 7 is at a level comparable to the frictional sound vibration detected by the rod portion 71, whereas the frictional sound obtained from the part fixedly arranged on the lifting platform 4. The vibration will be a significant level of damping. This is considered to be due to the influence of the bearing interposed between these parts, and it is considered that the propagation characteristics of the frictional sound vibration are lowered in this part by rolling the steel ball of the bearing. Against this background, the structure in which the contact member 18 is directly brought into contact with the penetrating rod 7 also by the structure in which the contact member 18 is brought into contact with the rotating portion of the chuck 5 such as the rod holding sleeve 53 as described above. It is possible to detect high-accuracy friction sound vibrations at a level comparable to that.
[0025]
【The invention's effect】
According to the present invention, it is possible to detect the frictional sound vibration from the penetration rod or the rotating portion that rotates integrally with the penetration rod. For this reason, for example, it is possible to detect the frictional sound vibration generated at the screw point more accurately than in the case where the frictional sound vibration is detected from a part fixed to the lifting platform or the like. In addition, it is possible to prevent surrounding noise elements from being mixed as compared with the conventional case where a microphone is used. Furthermore, since it is possible to detect frictional sound vibrations without using conventional wireless transmission / reception means, it is possible to simplify the circuit board and control method for detecting frictional sound vibrations. There are advantages such as being able to provide an automatic penetrometer with high functionality at a relatively low cost. On the other hand, since the means for allowing the screw point to rotate due to the resistance of the soil when the penetrating rod is self-sinking is provided, it is possible to penetrate naturally while rotating the screw point during self-sinking. Therefore, it is possible to properly generate frictional noise even during self-sinking, and this can be detected and the soil quality can be accurately determined. There are advantages such as being able to know.
[Brief description of the drawings]
FIG. 1 is an enlarged cross-sectional view of a main part of an automatic penetration testing machine according to the present invention.
FIG. 2 is an overall schematic explanatory view of an automatic penetration testing machine according to the present invention.
FIG. 3 is an enlarged cross-sectional view of the main part showing the vicinity of the chuck of the automatic penetration testing machine according to the present invention.
FIG. 4 is an enlarged cross-sectional view of a main part of another embodiment of the automatic penetration testing machine according to the present invention.
FIG. 5 is a front view of a conventional automatic penetration tester.
6 is an enlarged cross-sectional view of a main part taken along line AA in FIG. 5. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Automatic penetration test machine 2 Weight 3 Support | pillar 4 Lifting stand 5 Chuck 52 Rotating sleeve 53 Rod holding sleeve 6 Chuck drive motor 7 Penetration rod 71 Rod part 72 Screw point 73 Locking groove 8 Chain member 9 Sprocket 10 One-way clutch 11 Lift Motor 12 Brake means 13 One-way clutch 14 Sprocket 15 Endless chain 16 Sound detection mechanism 18 Contact member 19 Vibration detection sensor 23 Control unit

Claims (4)

A lifting platform that can be moved up and down along the column, a chuck that is rotatably provided on the lifting table, a rotation drive source that rotates the chuck, and a penetrating rod that is detachably attached to the chuck and is held rotatably. In an automatic penetration testing machine equipped with
A shaft-shaped contact member provided urging to abut constantly rotatable rotating portion integrally with the penetration rod or the penetration rod, the contact from the penetration rod or rotating parts attached to the contact member An automatic penetration testing machine comprising vibration detection means for detecting vibration transmitted to a member .   The vibration detection means detects vibration caused by a frictional sound transmitted to a contact member through a rotating portion that can rotate integrally with the penetrating rod from the screw point or through the penetrating rod or the penetrating rod. Item 2. An automatic penetration tester according to Item 1. Automatic penetration tester according to claim 1 or claim 2, characterized in that it comprises means to permit rotation of the screw point due to the resistance of the soil when the penetration rod is scuttled. The penetration rod is held in a chuck that is rotatably provided by the rotation drive source, and a load that is changed as necessary is applied to the penetration rod, and rotation is applied to the underground as necessary. Penetrated into
Vibration transmitted through the penetrating rod is detected through vibration detecting means attached to a shaft-shaped contact member that is urged so as to be always in contact with the penetrating rod or a rotating part that can rotate integrally with the penetrating rod. And
An intrusion test method characterized by determining soil quality based on the detected vibration.

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